Street sweeper main broom drive and support



0. T. LINK, JR., *ETAL July 21,- 1959 STREET SWEEPER MAIN BROOM DRIVE AND SUPPORT *1 Sheets-Sheet 1 Filed March a, 1955 5 5 r m w W I 69424:; 7.' luv/r, 1/2., Jamv 6T Goomf/v c. 'r. LINK, JR, ETAL 'July 21, 1959 v STREET SWEEPER MAIN BROOM DRIVE AND SUPPORT Filed March 8, 1955 7 Sheets-Sheet 2 lure-27. 27115 7 Me JOHN S. Goons/v July 21, 1959 c. T. LINK, JR. ETAL STREET swEEPER MAIN BROOM DRIVE AND SUPPORT F iled uarch 8; 1955 7 Sheets-Sheet 3 Ln En furs Cl/Aflid 2' 1/16/41 1/2, Joy/v 67 60011.5

I I H July 21, 1959 c. 1'. LINK, .13., 51-51. 2,895,150

STREET SWEEPER MAIN BROOM DRIVE AND SUPPORT 7 Sheets-Sheet 4 Filed March 8, 1955 lure .27- Tara Gaza-a Z' [mag/e Joy/v 6? 60005 K m 1.7 s.

July 21, 1959 c. r. VLINK,'JR., ETAL' 2,395,150

STREET SWEEPER MAIN BROOM DRIVE AND SUPPORT Filed March 8,v 1955 7 Sheets-Sheet 5 AVA'AYA'A ////////////A ////////////1 m 694211.: Z 1 /43 JR L/qmv Goamw July 21, 1959 c. T. LINK, JR., ETAL 2,895,150

smasr swsEPE-R MAIN BROOM DRIVE AND SUPPORT) Filed larch 8,1955 '7 Sheets-Sheet 6 1271 2177 UTE 0/4245: 2'' l/Me, Je. Jay/v 6. Goa/90v July 2 1, 1 959 c; TQLINK, J arm. 2,895,1

I STREET swEEPER MAIN BROOM-DRIVE AND SUPPORT I Filed llar'ch a, 1,955" '1 She ets-Sheet 7 Z 7I E.Z7Z UI 'E C/meLEs I Laws, (/6. 7 Jam 8. Gooozw United States Patent STREET SWEEPER MAIN BROOM DRIVE %AND SUPPORT Application 'March 8, 1955, Serial No. 492,859

4 Claims. (Cl. 15--83) This invention relates to a street sweeper 'main broom drive and support, the main broom of a street sweeper being a generally cylindrical brush-like structure rotatable on a transverse horizontal axis to throw dirt forwardly from the street surface either directly onto a dirt receptacle or preferably onto the lower end of an inclined conveyor which carries the dirt to a receptacle.

Heretofore, such main brooms have usually been supported by arms at opposite ends thereof pivoted on an axis in spaced parallel relation to the broom axis with the broom driven from a drive sprocket wheel rotatable on the pivot axis of such arms through a chain meshed with such sprocket wheel and a second sprocket wheel secured to the main broom.

With such support and drive arrangements, the horizontal forces resulting from brushing action of the broom on the street will tend to force the broom upwardly so that if a mass of relatively heavy thick material is contacted, the broom will tend to move upwardly and skim over the top of the material. In addition, as the diameter of the broom decreases, the point of engagement of the broom with the street may move rearwardly whereas it would be desirable to have the point of engagement move forwardly, or at least remain the same, for efiicient action. Further, it has not been possible to locate the pivot axis of thea'rins, and hence the driven sprocket wheel, at a point convenient for drive of the driven sprocket wheel from the engine of the sweeper.

An important object of this invention is to provide a support and drive arrangement for a street sweeper broom in which horizontal forces resulting from brushing action of the broom on the street will not affect the vertical position of the broom.

Another object of this invention is to provide an improved support arrangement for a street sweeper broom in which the broom may move freely up and down in response to variations in level of the street, without affecting the pressure of the broom on the street.

A further object of this invention is to provide an improved support and drive arrangement for a street sweeper broom which is readily and economically manufacturable, efficient and reliable in operation, durable and very compact, using a minimum number of parts.

The above and other objects, features and advantages of this invention will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate a preferred embodiment and in which:

Figure 1 is a side elevational view'of a rear portion of a street sweeper embodying a main broom drive and support arrangement constructed according to the principle'sof this invention;

Figure 1A is a reduced scale side elevational view of the complete street sweeper, illustrating the relationship of the main broom to a conveyor in the street sweeper;

Figure 2 is a sectional view taken substantially along line II--II of Figure 1;

Figure 3 is a sectional view, on an enlarged scale, taken substantially along line IIIIII of Figure 1;

Figure 4 is a sectional view taken substantially along line IV-IV of Figure 2;

Figure 5 is a sectional view taken substantially along line VV of Figure 4;

Figure 6 is a sectional view taken substantially along line VI-VI of Figure 2;

Figure 7 is a detail view on an enlarged scale of a portion of the main broom drive and support arrangement of Figure 1, with parts being broken away to more clearly illustrate the preferred construction;

Figure 8 is a sectional view taken substantially along line VIII-VIII of Figure 7; and

Figure 9 is a schematic diagram of a hydraulic system used in the machine of Figure 1.

Reference numeral 10 generally designates a street sweeper which may comprise a body 11 supported for movement along a street by a pair of front wheels 11a and a single steerable rear wheel 12. Disposed in front of the rear wheel 12 is a main broom 13 which may be supported for rotation on a transverse horizontal axis and which is arranged to engage the street surface indicated at reference numeral 14 and throw the dirt and refuse forwardly directly to a dirt receptacle or preferably onto the lower end of an inclined conveyor 11b which carries the dirt to a receptacle including a door 11c. The relation of the conveyor and dirt receptacle is illustrated diagrammatically in Figure 1A and is illustrated in more detail in the Link, Jr. et al. Patent No. 2,828,037 issued March 25, 1958 on an application filed September 24, 1954. This invention is concerned primarily with the support and drive of the main broom 13.

Before proceeding with a detailed description of the main broom drive and support, it may be noted that in order to conserve materials and make the sweeper as compact and maneuverable as possible, the rearward end of the body 11 may be tapered to a rounded rear end as best shown in Figure 2, such rounded rear end being defined by left-hand and right-hand side walls 15 and 16 integrally joined at the rear extremity of the sweeper. This form of the body 11 is, of-course, made possible by the use of the single centrally located rear wheel 12. The body 11 also includes a horizontal plate 17 positioned between the side walls 15 and 16 at a level slightly above the upper end of the rear wheel 12 and an inverted channel-shaped bracket 18 extending transversely between the side walls 15 and 16 and disposed on the plate 17 over the rear wheel 12.

To drive the front traction wheels and other parts of the sweeper, an engine is positioned between the side walls 15 and 16 above the level of the plate 17. For convenience of illustration, the engine and support therefor are not shown in the drawings, except that an extreme rearward end portion 19 of the engine is illustrated in Figure 2 above the bracket 18 with the rear end 20 of the engine drive shaft projecting rearwardly from the portion 19.

Secured to the drive shaft rear end portion 20 are a pair of pulleys 21 and 22. The pulley 21 is used to drive the main broom 13. It is not essential to the present invention, but it may be noted that the pulley 22 drives a belt 23 which is trained about and drives pulleys 24 and 25 journaled for rotation on spaced vertically aligned horizontal axes by an upright leg 26 of a bracket 27 having a horizontal leg 28 bolted or otherwise secured on the bracket 18. The pulleys 24 and 25 drive hydraulic pumps 29 and 30, respectively, and the lower pulley 24 may also drive a water pump 31.

The hydraulic pump 29 may, for example, supply fluid under pressure for drive and control of a side broom, not shown, while the hydraulic pump 30 may supply fluid under pressure for actuation of a conveyor, not shown, and for elevating the main broom 13 in a manner as will be described hereinafter.

According to this invention, the broom 13 is journaled between lower end portions of a pair of transversely spaced support means generally designated by reference numerals 32 and 33 adjacent the left-hand and right-hand side walls 15 and 16, respectviely, on opposite sides of the engine. These support means 32 and 33 may preferably be generally upright as illustrated so as to occupy mini mum space in a direction parallel to the direction of movement of the sweeper. For drive of the main broom 13, the left-hand support means 32 may carry drive-transmitting means generally designated by reference numeral 34 at the upper end thereof, the drive-transmitting means 34 being coupled through a chain drive to be described in detail hereinafter to the broom 13 and also being coupled through a universal coupling arrangement generally designated by reference numeral 35 to a pulley 36 through a hydraulically controlled clutch 37 mounted on the bracket 18, the pulley 36 being coupled by a belt 38 to the pulley 21 on the rearwardly projecting drive shaft portion 20. The drivetransmitting means 34 and the universal coup-ling arrangement 35, as well as the chain drive from the drivetransmitting means 34 to the main broom 13, will all be described in detail hereinafter.

According to a specific feature of the invention, the

support means may be connected to the body 11 by means allowing bodily displacement thereof in a generally vertical direction to prevent rearward movement of the broom axis with decreasing broom diameter. This bodily movement in a vertical direction is particularly advantageous because it permits the vertical adjustment of the axis of the broom 13 with a very compact arrangement of parts. With pivotal supports heretofore used, movement of the axis of the broom in a direction parallel to the movement of the sweeper could not be limited without using very long pivotal arms. It should be noted that by limiting movement of the broom axis in a direction parallel to the direction of movement of the sweeper, the broom may be located very close to the wheel 12 and'yet in properly spaced relation to the conveyor, or dirt receptacle receiving dirt from the broom 13, and hence the wheel base and overall length of the sweeper may be reduced to a minimum. Preferably the support means 32 and 33 are so connected to the body 11 that the axis of the broom 13 moves slightly forwardly as the diameter of the broom decreases, so as to achieve optimum brushing action.

For this purpose, the support means 32 and 33 could be mounted for slidable movement in suitable ways of the body 11 but preferably, each of the support means is connected to the body through a pair of links in a manner such that the axis of the broom 13 is displaceable in a substantially vertical direction.

In particular, the upper end portions of the support means 32 and 33 may be connected to the body 11 through a pair of links 39 and 40 disposed above the plate 17 and portions of the support means 32 and 33 disposed below the plate 17 may be connected to the body 11 through links 41 and 42. In more detail, the links 39 and 40 may have rearward end portions pivoted to brackets 43 and 44, respectively, bolted to the bracket 18 adjacent the side walls 15 and 16, respectively, and the links 39 and 40 may have bifurcated forward end portions receiving and pivotally secured to lugs 45 and 46 projecting rearwardly from the support means 32 and 33 adjacent the upper ends thereof. The links 41 and 42 may have rearward end portions pivotally secured to brackets 47 and 48 secured to the left and right hand side walls 15 and 16, respectively, and the lower links 41 and 42 may have forward end portions pivotally secured to lugs 49 and 5t] projecting rearwardly from the support means 32 and 33, respectively, below the plate 17.

The connection of the support means 32 and 33 to the body 11 through the links 3942 is particularly advantageous because it is very simple and comparatively inexpensive, has very little friction, and provides a positive support of the support means 32 and 33. At the same time, it is possible to obtain substantially vertical movement of the axis of the main broom 13 which, as pointed out heretofore, is a distinct advantage. Further, the upper end portions of the support means are movable in generally arcuate paths which is of advantage in obtaining a proper drive connection between the engine and the drive-transmitting means 34.

it will be appreciated that the path of movement of the axis of the broom 13 with pivotal movement of the links 39-42 is determined by a number of factors including the vertical spacings of the pivot axes of connection of the links 39-42 to the sweeper body 11 from each other and from the level of the street, the horizontal spacing of such axes, the lengths of the links, the spacing between the axes of connection of the links to the support means and the position of the broom axis relative to the axes of connection of the links to the support means. In the design of the sweeper, all but one or two of such factors may be adjusted to suit the practical requirements for mounting of the support means 32 and 33 and such one or two remainng factors may then be readily adjusted by a simple trial and error method to obtain substantially vertical movement of the broom axis through the desired range. i

It may be noted that the optimum condition is obtained when the ratio of an incremental horizontal displacement of the broom axis in a forward direction relative to a corresponding incremental decrease in thespacing of the broom axis from the support surface is slightly positive with the spacing of the broom axis from the supporting surface within the desired range of broom radii. Accordingly, if extreme accuracy is desired, a mathematical operation may be used to determine the optimum relation of the factors, by obtaining an expression for the horizontal displacement of the broom axis in terms of the various factors and the spacing of the broom axis from the supporting surface, obtaining the derivative of such expression with respect to such spacing, and setting such derivative equal to a small value.

By way of specific example and not by way of limitation, the spacing between the pivot axes of the top link may be eighteen and one-half inches, the spacing between the pivot axes of the bottom links may be thirtysix inches, the axis of connection of the bottom links to the body from the street surface may be twenty-five inches, the horizontal spacing of the axes of connection of the links to the body may be twelve and one-half inches, the vertical spacing of the axes of connection of the links to the body may be twenty-seven and one-half inches, the spacing of the axes of connection of the links to the support means may be twenty-seven inches, the axis of the broom may be spaced six and one-half inches from a line through the axes of connection of the links to the support means and the axis of the broom may be seventeen and one-fourth inches from the axis of connection of the lower links to the support means.

With these spacings, the broom axis may move forwardly about three-fourths of an inch with the spacing of such axis from the street surface changed from eighteen inches to ten inches. Hence the sweeper will readily accommodate brooms of between twenty and thirty-six inches in diameter.

The parts may, for example, be in a position as illustrated in full lines in Figure 6 with a broom of thirtysix inch diameter and may be in a position as illustrated in dotted lines in Figure 6 with a broom of twenty inches in diameter.

According to a further feature of the invention, the vertical position of the support means 32 and 33 is controlled by fluid-actuated means which may comprise a pair of hydraulic rams 51 and '52 comprising pistons 53 and 54 having upper ends pivoted in slots 55 and 56 in the links 39 and 40 and having lower ends movable in cylinders 57 and 58 which extend through openings in the plate 17 and have lower'ends secured to brackets 59 and 60 which are, in turn, secured to the side plates and 16 below the plate 17.

The operation of the hydraulic rams 51 and 52 to achieve instant pressure engagement between the broom and the street is a very important feature of the invention and will be described in detail hereinafter in connection with the hydraulic central circuit of Figure 9.

As indicated above, the left-hand support means 32, in addition to journaling one end of the broom 13, also houses the drive-transmitting means 34 and a chain coupling from the drive-transmitting means 34 to the broom 13. For these purposes, the support means 32 may comprise a three-part housing including a lower member 61, an intermediate member 62 and an upper member 63 rigidly secured together. It may be noted that the upper housing member carries the lug 45 pivoted to the link 39 whilethe intermediate housing member 62 carries the lug 49 pivoted to the link 41.

The lower housing member 61 of the left-hand support means 32 is arranged to journal one end of the broom 13. For this purpose, the lower housing member 61 may have an opening in the inwardly facing wall thereof closed by a bearing support plate 64 bolted or otherwise secured thereto. The bearing support plate 64 has a central opening therein in which a shaft 65 is journaled. To this end, the plate 64 carries within the central opening therein inner and outer bearing members 66 and 67 having radially inwardly facing oppositely inclined frusto-conical bearing races and the shaft 65 carries bearing members 68 and 69 having outwardly facing oppositely inclined frusto-conical bearing races in opposed relation to the races of members 66 and 67, respectively, with rollers 70 disposed between the races of members 66 and 68 and with rollers 71 disposed'between the races of members 67 and 69. Inclination of the faces is such as to oppose inward movement of the outer bearing member 69 and outward movement of the inner beari-ngmember 68. To limit inward movement of the shaft 65, it may have an annular flange portion 72 at its outer end engaged with the bearing member 69 and a collar 73 may be secured on the inner end of the shaft 65 inside and in engagement with the bearing member 68. A seal generally designated by reference numeral 74 may be provided between the collar 73 and the bearing support plate 64.

The collar 73 may preferably be removably secured on the inner end of the shaft 65 by means of a block 75 secured against the. inner end of the shaft 65 by a screw 76 and secured to the inner surface of the collar 73 by screws 77. To positively prevent rotation of the collar 73 so asto eliminate torsion on the screw 76, a key 78 may be provided between the collar 73 and the shaft 65.

The block 75, in addition to serving as a means securing the collar 73 to the shaft 65 also serves me support means for the left-hand end of the broom 13. To this end, theblock 75 may have a plurality of circumferentially spaced radially outwardly projecting axially extending teeth 79 engageable in complementarily shaped recesses in the inner surface of a collar 80 to provide a spline connection therebetween.

For support of the broom 13 from the collar 80, the collar 80 at its outer end may have an outwardly projecting annular flange portion 81. A sleeve 82 has an inner end portion around the annular flange portion 81 of the collar 80 and has a radially inwardly projecting annular flange portion 83 abutting the inwardly facing surface of the flange portion 81 of the collar 80. A tube 84 of sheet metal may extend between the support means 32 and 33 and may have a cross-sectional shape generally the same as an equilateral triangle with the apices at the left-hand end thereof being welded or otherwise rigidly secured to the flange 83 of the sleeve 82.

The brush 13 may be formed by winding a generally channel-shaped member 85, one end portion of which is shown in cross-section in Figure 8, about the sleeve 82 and tube 84 with a cable (not shown) disposed in the channel member 85 and with brush material (also not shown) folded about the cable within the channel member 85 so that the ends of the material project radially outwardly. Any suitable brush construction could, of course, be used.

An annular end plate 86 may abut a radially outwardly projecting flange 87 at the outer end of the sleeve 82 and may have an inwardly extending sleeve portion 88 disposed within the sleeve 82 with a radially inwardly projecting integral flange portion 89 at the inner end of the sleeve portion 88 secured to the flange portion 81 of the support collar 80 by one or more screws 90 extending through the flange portion 81 and threaded into the flange portion 83 of the collar 82.

As indicated heretofore, a chain drive coupling is provided in the left-hand support means 32 between the drive-transmitting means 34 and the broom 13. This drive coupling may comprise a sprocket 91 rigidly secured against the flange portion 72 at the outer end of the shaft 65 by screws 92 within the lower housing member 61. Access to the sprocket wheel 91 and associated parts may be provided by a removable cover plate 93 closing an opening in the outer wall of the lower housing member 61.

An endless drive chain 94 is trained about and in mesh with the sprocket 91 and is also trained about and in mesh with a sprocket 95 journaled in the upper housing member 63. To maintain proper tension in the chain 94 and to prevent the chain from slapping against the inner surfaces of the housing members 61, 62 and 63, a pair of idler sprockets 96 and 97 may mesh with opposite sides of the chain 94. The idler sprockets 96 and '97 may be journaled on a plate 98 afiixed within the intermediate housing member 62.

For drive of the upper sprocket 95, it may be rigidly secured by means such as screws 99 to a hub portion 100 of a gear 101 forming part of the drive-transmitting means 34, the hub portion 100 of the gear 101 in turn, being secured by a set screw 102 on the outer end of a shaft 103 journaled within the upper housing member 63.

To journal the shaft 103, a bearing support member 104 may be secured by screws 105 to a plate 106 which closes an opening in the inwardly facing wall of the housing member 63 and which is secured to the housing member 63 by screws 107.

The bearing support member 104 may have a hollow boss portion 108 receiving the shaft 103 and carrying outer and inner bearing members 109 and 110 having radially inwardly facing oppositely inclined frusto-conical bearing races and the shaft 103 may carry outer and inner bearing members 111 and 112 having radially outwardly facing oppositely inclined frusto-conical bearing races in opposed relation to the races of members 109 and 110 with rollers 113 and 114 disposed between the races of members 109 and 111 and with rollers 114 disposed between the races of members 110 and 112. The bearing races may be so inclined as to oppose inward movement of the outer bearing member 111 and as to oppose outward movement of the inner bearing member 112.

To limit inward movement of the shaft 103, the gear 101 may abut the bearing member 111 and to oppose outward movement of the shaft 103, a nut 115 may be threaded on the inner end of the shaft 103 for engagement with the bearing member 112. It will be appreciated that this bearing support permits free rotation of the shaft 103 while preventing axial movement thereof.

For drive of the gear 101, it may have a toothed peripheral rim portion .116 which may preferably be disposed in inwardly spaced relation to the hub portion 100 and in surrounding relation to a portion of the boss 108 so as to achieve themost compact assembly possible. The tooth peripheral rim portion 116 is meshed with a worm 117 secured to a shaft 118 by means including a key. 119.

The shaft 118 may be journaled for rotation in the upper housing member 63 by a bearing arrangement including a pair of members 120 and 121 secured within the housing member 63 and having radially inwardly facing oppositely inclined frusto-conical bearing races and a pair of bearing members 122 and 123 disposed on the shaft 118 and having radially outwardly facing oppositely inclined frusto-conical bearing races in opposed relation to the races of members 121) and 121 with rollers 124 disposed between the races of members 126 and 122 and with rollers 125 disposed between the races of members 121 and 123. The inclination of the bearing races is such as to oppose movement of the bearing members 122 and 123 away from each other, and movement of such bearing members toward each other may be prevented by engagement thereof with the opposite ends of the worm v11'7. The, shaft 118 may be secured in position relative to the bearing members 122 and 123 by means including a lock nut 126 threaded on one end of the shaft 118.

Secured to the other end of the shaft 118 is the universal coupling member 127 forming part of the universal coupling generally designated by reference numeral 35 and having a bifurcated end portion arranged to journal a pin 128. Another coupling member 129 is journaled on transversely projecting portions of the pin 128' formovement about an axis transverse to the pivotal axis of the pin 128 relative to the coupling member 127, thus providing the universal connection.

The coupling member 129 may be carried by a rod 130 t'elescoped within a tube 131 with a suitable spline connection between the rod 130 and tube 131 to lock the same against relative rotation while permitting relative axial movement thereof. The tube 131 may carry a coupling member 132 similar to the coupling member 129 and having a bifurcated portion pivotally receiving transversely extending portions of a pin 133 journaled in a bifurcated portion of a coupling member 134 similar to the coupling member 127, thus providing another universal connection. The coupling member 134 may be secured to the pulley 36 so as to be driven thereby. It may be noted that by virtue of the pivotal support of the upper end portion of the support means 32 from the body 11 through the link 39, the relative telescoping movement of the rod 130 in the tube 131 is reduced to a minimum.

It may also be noted that the support means 32 and 33 are located closely adjacent the side walls 15 and 16 while the coupling assembly 35 as well as the links 39 and 46 extend in relatively closely spaced relation to the side walls so as not to interfere with the support of the engine and so as to permit the engine to be as far to the rear as possible and yet utilize the tapered rearward end shape of the sweeper body 11. The ultimate result in that the wheel base and overall length of the sweeper may be as short as possible with the sweeper as readily maneuverable as is possible.

If desired, the right-hand support means 33 as well as the left-hand support means 32 might carry drive means for the broom 13. Such is not necessary, however, partic'ularly with the positive connection of the support means 32 and 33 to the body as is obtained with the links 39-42. Accordingly, the support means 33 need only journal the right-hand end of the broom 13.

The support means 33 may comprise an upper member 135 which may have the lugs 46 and 50 formed as an integral part thereof, and a lower member 136 arranged to journal the right-hand end of the brush 13. For this purpose, the support member 136 may journal a shaft 137, similar to the shaft 65 in the left-hand support, by heating means including bearing members 138, 139, 140

and 141 similar to the .bearing members 66, 67, 68 and 69, respectively, in the left-hand support, with rollers 142 disposed between the races of bearing members 138 and and rollers 143 disposed between the races of bearing members 139 and 141.- A spring retaining washer arrangement 144 may engage the outer bearing member 141 to limit inward movement of the-shaft 137.

Disposed on the inner end of the shaft 137 is a collar 145 identical to the collar 73 in the left-hand support with a seal 146 similar to the seal 74 in the left-hand support. A block 147 identical to the block 75 may be secured to the shaft 137 and to the collar 145 through bolts 148 and 149 corresponding to the bolts 76 and 77, respectively, the block 147 having circumferentially spaced radially outwardly projecting teeth 150 engaged in recesses in a collar 151 corresponding to the collar 80 in the left-hand support. The collar 151 has an integral flange portion 152 on which is mounted a sleeve 153 corresponding to the sleeve 82 in the left-hand support, the right-hand end of the tube 84 being welded or otherwise suitably secured to the sleeve 153. An end plate 154 corresponding to the end plate 86 in the left-hand support may be secured in assembly with the sleeve 153 and the flange 152. v

To balance the support means 32 and 33, the upper member 135 of the support means 33 may be at least partially filled with slugs 155 or the like of heavy material such as metal having a weight equal to the ditference in the Weight of the support means 32 and 33 without such material. With this ballast, the pressure exerted by the broom on the street can be uniform from one end of the broom to the other.

It should be noted that a highly important advantage of the support and drive arrangement described above is that the forces exerted by the broom drive means have no efiect upon the vertical position of the broom or the pressure exerted by the broom on the street surface.

Referring now to Figure 9', the pump 30 supplies fluid under pressure from a reservoir 156 to one section 157 of a distributing valve 158 having a second section 159 connected to the reservoir 156. A relief valve 160 is provided between the outlet of the pump 30 and the reservoir 156.

By actuation of the distributing valve 158, fluid under pressure may be applied from the pressure section 157 through a conduit 161' and through a reversing valve 162 to a motor 163 arranged for driving the conveyor 1117 as diagrammatically illustrated in Figure 1A. Fluid from the outlet side of the motor 163 passes back through the reversing valve 162, through a conduit 164 and through a check valve 165 to a point 166 of the hydraulic circuit. The point 166 is connected through a pressureregulating valve 167 and through a conduit 168 to the reservoir section 159 of the distributing valve 158. The operation of the valve 167 is such that an adjustable constant pressure is maintained at the point 166.

The constant-pressure point 166 is connected through conduits 169 and 170 to the hydraulic rams 51 and 52 which control raising and lowering of the main broom supports. Thus a constant pressure is exerted on the main broom and, irrespective of the vertical position of the main broom, there will always be the constant pressure between the main broom and the street surface.

The constant pressure regulating valve 167 may be of any desired construction, but is adjustable to allow for adjustment of the pressure between the main broom and the street surface.

To elevate the broom out of engagement with the street-surface, the distributing valve 158 is arranged to divest fluid under pressure through the conduit 168 and through a check valve 171 to the rams 51 and 52, the check valve 165 being then eifective to prevent back flow of fluid through the motor 163.

It may be noted that the point.166 may also be connested through the conduit 169 and through a conduit 9 172 to a pair of hydraulic rams 173 and 174 which control vertical positioning of the conveyor, not shown.

According to a specific feature of the invention, the outlet of the pressure section 157 of the distributing valve 158 that is connected to the conduit 161 is also connected through conduits 175 and 176 to a hydraulic motor 177 which controls the clutch 37, so as to initiate drive of the main broom at the same time that the main broom is lowered.

The conduit 175 may also be connected through a check valve 178 and through a control valve 179 to a hydraulic motor 180 which controls tensioning of a belt of the conveyor structure not shown.

The pressure section 157 of the distributing valve 158 may have a second outlet connected to rams 181 and 182 which control a dirt box assembly of the street sweeper. A pilot-operated valve 183 is provided which blocks ofi fluid flow from the rams 181 and 182 to the reservoir except when fluid under pressure is applied from the pressure section 157 of the distributing valve 158, so as to lock the dirt box assembly into any position in which it is actuated.

The dirt box assembly may preferably take the form disclosed in the copending application of Charles T. Link, Jr., Robert F. Schmidt and John S. Gooden entitled Street Sweeper Dirt Box Assembly, filed September 24, 1954, US. Serial No. 458,176 now Patent No. 2,828,037.

It may be noted that any type of pressure regulating system may be utilized to insure constant pressure engagement between the main broom and the street. The system disclosed is, however, preferred in that the conveyor motor 163 serves to drop the pump pressure down to the pressure desired for actuation of the main broom control cylinders 51 and 52. Also, of course, a minimum number of parts are required.

As previously indicated the support and drive of the broom is such that driving forces do not exert any net vertical force on the broom. In particular, the brushing action of the broom on the street creates horizontal forces in the broom supports which cause vertical forces where the upper and lower links are connected to the broom supports, but such vertical forces are in balanced opposed relation, by virtue of the relation of the links as described above, so that there is substantially no net vertical force on the broom supports.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. In a street sweeper including a wheeled body having ahorizontal plate therewithin, a pair of transversely spaced upright support means extending through said plate, a broom journaled between lower end portions of said support means, and means connecting said support means to said body including a first pair of links connected between said body and said support means below said plate, and a second pair of links connected between said body and said support means above said plate, said 10 links being so arranged that the axis of said broom is displaceable in a substantially vertical direction.

2. In a street sweeper including a wheeled body having a horizontal plate therewithin and an engine supported therewithin above said plate, a pair of transversely spaced upright support means extending through said plate on either side of said engine, a broom journaled between lower end portions of said support means, means connecting said support means to said body for vertical movement including a first pair of links connected between said body and said support means below said plate, a second pair of links connected between said body and said support means above said plate, drive-transmitting means in the upper end of one of said support means, means coupling said drive-transmitting means to said engine, and means in said one of said support means coupling said drive-transmitting means to said broom.

3. In a street sweeper including a wheeled body having a tapered rearward end portion defined in part by convergent side walls and an engine supported in said body having a rearwardly projecting crank shaft portion, a pair of transversely spaced upright support means carried by said body on opposite sides of said engine, a broom journaled between lower end portions of said upright support means, drive-transmitting means at the upper end of at least one of said suppont means, means in said one of said support means coupling said drivetransmitting means to said broom, a drive element adjacent one of said convergent side walls coupled to said rearwardly projecting crank shaft portion of said engine, and coupling means extending from said drive element forwardly along said one of said convergent side walls to said drive-transmitting means.

4. In a street sweeper including a wheeled body, conveyor means within said body including a drive motor and a broom carried by said body for engaging with the street surface to throw dirt therefrom to the conveyor, fluid-actuated means mechanically connected to said broom to control the sweeping pressure between the broom and the street surface, a reservoir, a pump having an inlet connected to said reservoir and having an outlet, a pressure-regulator valve connected to said reservoir, means connecting said conveyor drive motor between said pump outlet and said pressure regulator valve, and means connecting said pressure-regulator valve to said fluid-actuated means for maintaining a substantially constant sweeping pressure.

References Cited in the file of this patent UNITED STATES PATENTS 901,154 Crozier Oct. 13, 1908 1,176,825 Federici Mar. 28, 1916 2,278,306 Cushman et a1 Mar. 31, 1942 2,314,381 Arnett Mar. 23, 1943 2,732,573 Hyland Jan. 31, 1956 FOREIGN PATENTS 651,826 Great Britain Apr. 11, 1951 695,207 Great Britain Aug. 3, 1953 

